The present invention relates to a method of, and to an apparatus for, conveying printed products in imbricated formation with different spacings between successive products, from a feed conveyor to the grippers on a removal conveyor. Such a method and such an apparatus are suitable, in particular, for conveying newspapers and periodicals as well as parts thereof and inserts therefor.
CH-A-630 583 and the corresponding U.S. Pat. No. 4,320,894 disclose a method and an apparatus of the abovementioned type wherein the drives for the feed conveyor and the removal conveyor are independent of one another, that is to say there is no correlation of the conveying speed of the removal conveyor to the timed sequence of the arriving printed products conveyed by the feed conveyor. This means that, on the one hand, the grippers grip a different number of printed products and, on the other hand, the printed products reaching the transfer location may not necessarily come into contact with a gripper. For this reason, the following precautions are taken in order nevertheless to ensure that the printed products are received satisfactorily by in each case one gripper:
Arranged in the transfer region are stop rails against which a printed product which reaches the transfer region earlier than the associated gripper strikes. A printed product butting against the stop rails is prevented from moving any further forward until such time as it is carried along by the associated gripper. Also provided in the transfer region is a deflecting arrangement which has a rotating wheel which is driven by the feed conveyor and on which resilient deflecting fingers are fastened. These deflecting fingers are deflected in each case, by the trailing clamping part of the grippers, into an active position, in which the deflecting fingers serve as a stop for printed products reaching the transfer region late. The printed products positioned against a deflecting finger are deflected downward, out of the normal conveying path, in the region of their leading edge and braked in the process and subsequently then fed to the next gripper.
These two measures taken in the case of the known apparatus ensure that all the printed products are gripped satisfactorily by in each case one gripper, but, as has been mentioned, cause the printed products reaching the transfer region to be braked. This braking of the printed products results in a reduction in the spacing between the braked printed products and the respectively following products. In other words, there is a change in the imbricated formation as it is transferred from the feed conveyor to the removal conveyor.
It is known from EP-A-0 330 868 and the corresponding U.S. Pat. No. 4,953,847 for the printed products which are fed in an imbricated formation, with uniform spacings between the respectively successive printed products, to a transfer location to be received by a removal conveyor with grippers in such a way that each gripper grips in each case two printed products, with the spacing of the latter in the imbricated formation being maintained. This is achieved in that the feeding speed of the feed conveyor and the conveying speed of the removal conveyor are selected such that, during the time in which the fed printed products cover double the spacing between two printed products, the grippers of the removal conveyor cover a distance which corresponds to the fixed spacing between two grippers.
The object of the present invention, then, is to provide a method and an apparatus of the type mentioned in the introduction which make it possible, in a straightforward manner, for the printed products which are fed with irregular mutual spacings to the transfer location to be received satisfactorily and carefully by the grippers of the removal conveyor without it being necessary, for this purpose, for individual products to be braked and displaced.
The above and other objects and advantages of the invention are achieved by the provision of a method and apparatus wherein the printed products are introduced into the grippers of the removal conveyor without any change in the spacing between successive printed products, so that each gripper grips the number of printed products fed to it with the same mutual spacing as in the imbricated formation. Also, once a number of printed products have been received by a gripper, the following printed products are directed into an open mouth of the next gripper, with the spacing being maintained between the last printed product gripped by the preceding gripper and the following printed product.
The present invention is based on the finding that the printed products can be transferred from the feed conveyor to the removal conveyor, while maintaining their mutual spacing, if it is ensured that, on the one hand, the printed products running into a gripper in each case are not inhibited in their forward movement prior to the closure of the gripper and, on the other hand, the following printed products which cannot be gripped correctly by the preceding gripper are directed to the open mouth of the next gripper while maintaining their mutual spacing.